Methods, apparatuses and computer-readable storage mediums for coordinated selection of ran and core user plane components in a wireless communications network

ABSTRACT

A server associated with a core network may include a memory storing computer-readable instructions; and at least one processor coupled to the memory, the at least one processor configured to execute the computer-readable instructions to, generate a list of preferred instances of a first network function, transmit the list of the preferred instances to a server associated with a third network function, and receive a request to establish a communication session with a selected instance selected from the list of the preferred instances, if the server is associated with a selected instance of a second network function associated with the selected instance of the first network function.

BACKGROUND Field

One or more example embodiments relate to methods, apparatuses and/orcomputer-readable storage mediums to coordinate selection of a radioaccess network (RAN) and core user plane (UP) components in a wirelesscommunications network.

Discussion of Related Art

Developments in the Third-Generation Partnership Project (3GPP) 5thGeneration networks have trended towards allowing a separation of userplane and control plane processing in the Radio Access Network (RAN) aswell as a Core Network. The 5th Generation networks also allow differentcomponents to be placed at different locations in the network. It isexpected that these networks will carry high volumes of data traffic,leading to a need for optimized processing of the data traffic in thenetwork.

SUMMARY

Some example embodiments relate to a server associated with a corenetwork. In some example embodiments, the server may include a memorystoring computer-readable instructions; and at least one processorcoupled to the memory, the at least one processor configured to executethe computer-readable instructions to, generate a list of preferredinstances of a first network function, transmit the list of thepreferred instances to a server associated with a third networkfunction, and receive a request to establish a communication sessionwith a selected instance selected from the list of the preferredinstances, if the server is associated with a selected instance of asecond network function associated with the selected instance of thefirst network function.

In some example embodiments, the first network function is a CentralizedUnit-User Plane (CU-UP) function having a CU-UP instance associatedtherewith, the list of preferred instances is a list of preferred CU-UPinstances configured to perform of the CU-UP function, and the selectedinstance is a selected CU-UP instance selected from the list ofpreferred CU-UP instances, the second network function is a User PlaneFunction (UPF) having a UPF instance associated therewith and theselected instance of the second network function is a selected UPFinstance, and the third network function is at least one of a SessionManagement Function (SMF) having a SMF instance associated therewith anda Network Repository Function (NRF) Function having a NRF instanceassociated therewith.

In some example embodiments, the at least one processor is configured toexchange information with a Radio Access Network (RAN) server, theinformation including one or more of load information of each of theserver and the RAN server, latency information of each of the server andthe RAN server, and proximity information indicating a distance betweenthe server and the RAN server.

In some example embodiments, the at least one processor is configured togenerate the list of the preferred CU-UP instances based on theinformation exchanged with the RAN server.

In some example embodiments, the at least one processor is configured toat least one of: exchange information with the RAN server over an N3interface, and transmit the list of the preferred CU-UP instances to theSMF instance over an N4 interface.

In some example embodiments, the at least one processor is configured togenerate the list of the preferred CU-UP instances such that thepreferred CU-UP instances are ones of a plurality of CU-UP instancesthat are one or more of (i) relatively closer to the server in regardsto geographical or network topology and (ii) relatively lower in latencyto the server as compared to other ones of the plurality of CU-UPinstances.

In some example embodiments, the at least one processor is configured torun a UPF instance, the UPF instance being co-located with at least oneof the plurality of CU-UP instances included in the list of thepreferred CU-UP instances.

In some example embodiments, the server is configured to perform the UPFfunction for a user equipment (UE), and the selected CU-UP instance isconfigured to perform a CU-UP function for the UE.

In some example embodiments, the selected CU-UP is selected by the RANserver based on a distance between a Centralized Unit-Unit Plane (CU-CP)instance associated with the RAN server and the selected CU-UP instanceassociated and the selected UPF instance.

In some example embodiments, the selected CU-UP is co-located with theCU-CP instance associated with the RAN server.

Some other example embodiments relate to a server associated with aRadio Access Network (RAN). In some example embodiments, the server mayinclude a memory storing computer-readable instructions; and at leastone processor coupled to the memory, the at least one processorconfigured to execute the computer-readable instructions to, receive alist of preferred Centralized Unit-Unit Plane (CU-UP) instances from aserver associated with a core network, select a selected CU-UP instancebased on the list of the preferred CU-UP instances, and establish acommunications session with the selected CU-UP instance.

In some example embodiments, the at least one processor is configuredto, receive an identifier of a User Plane Function (UPF) instance from aserver associated with the core network, and provide the identifier ofthe UPF instance to the selected CU-UP instance.

In some example embodiments, the at least one processor is configured toselect the selected CU-UP instance such that the CU-UP instance isco-located with at least one Centralized Unit-Unit Plane (CU-CP)instance.

In some example embodiments, the list of the preferred CU-UP instancesis generated based on information exchanged between the CU-UP instancein the RAN and a User Plane Function (UPF) instance in a Core Network.

In some example embodiments, the information exchanged between the RANserver and the Core Network includes one or more of load information ofeach of a server in the core network and the RAN server, latencyinformation of each of the server in the core network and the RANserver, and proximity information indicating a distance between theserver in the core network and the RAN server.

Some other example embodiments relate to another server associated withthe core network. In some example embodiments, the server may include amemory storing computer-readable instructions; and at least oneprocessor coupled to the memory, the at least one processor configuredto execute the computer-readable instructions to, select a User PlaneFunction (UPF) instance from among a plurality of UPF instances, query aNetwork Repository Function (NRF) instance for a list of preferredCentralized Unit-User Plane (CU-UP) instances, and transmit the list ofthe preferred CU-UP instances to a Centralized Unit-Unit Plane (CU-CP)instance.

In some example embodiments, the CU-CP instance selects a selected CU-UPinstance from among the list of the preferred CU-UP instances.

In some example embodiments, the at least one processor is configured tohost a Session Management Function (SMF) instance.

In some example embodiments, the at least one processor is configuredto, receive the list of the preferred CU-UP instances from one of theplurality of UPF instances, and transmit the list of the preferred CU-UPinstances to the NRF instance prior to performing an attach procedurewith a user equipment (UE).

In some example embodiments, the at least one processor is configuredto, query the NRF instance for the list of the preferred CU-UP instancesand transmit the list of the preferred CU-UP instances to the CU-CPinstance after completing an attachment procedure with the UE.

BRIEF DESCRIPTION OF THE DRAWINGS

Some example embodiments will become more fully understood from thedetailed description given herein below and the accompanying drawings,wherein like elements are represented by like reference numerals, whichare given by way of illustration only and thus are not limiting of theexample embodiments.

FIG. 1 illustrates a 3GPP 5G system architecture according to someexample embodiments;

FIG. 2 illustrates a Radio Access Network (RAN) in a 5G networkaccording to some example embodiments;

FIG. 3 illustrates a relevant portion of the 3GPP 5G system architectureaccording to some example embodiments;

FIG. 4 is a block diagram illustrating the structure of a serverassociated with a radio access network (RAN) according to some exampleembodiments;

FIG. 5 is a block diagram illustrating the structure of a serverassociated with a core network according to some example embodiments;

FIG. 6 is a signal flow diagram illustrating a procedure to enablecoordinated selection of a UPF instance by an SMF and a CU-UP instanceby the RAN, taking into account preferred relationships between certaininstances of UPF and CU-UP, according to some example embodiments; and

FIG. 7 is a signal flow diagram illustrating a procedure to enablecoordinated selection of a UPF instance by an SMF and a CU-UP instanceby the RAN, taking into account the preferred relationships betweencertain instances of UPF and CU-UP according to some exampleembodiments.

It should be noted that these figures are intended to illustrate thegeneral characteristics of methods, structure and/or materials utilizedin certain example embodiments and to supplement the written descriptionprovided below. These drawings are not, however, to scale and may notprecisely reflect the precise structural or performance characteristicsof any given embodiment, and should not be interpreted as defining orlimiting the range of values or properties encompassed by exampleembodiments. The use of similar or identical reference numbers in thevarious drawings is intended to indicate the presence of a similar oridentical element or feature.

DETAILED DESCRIPTION

Various example embodiments will now be described more fully withreference to the accompanying drawings in which some example embodimentsare shown.

Detailed illustrative embodiments are disclosed herein. However, thespecific structural and functional details are merely representative forthe purposes of describing example embodiments. The example embodimentsmay, however, be embodied in many alternate forms and should not beconstrued as limited to only the embodiments set forth herein.

It should be understood that there is no intent to limit exampleembodiments to the particular forms disclosed. On the contrary, exampleembodiments are to cover all modifications, equivalents, andalternatives falling within the scope of this disclosure. Like numbersrefer to like elements throughout the description of the figures. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. Other words used to describe therelationship between elements should be interpreted in a like fashion(e.g., “between” versus “directly between,” “adjacent” versus “directlyadjacent,” etc.).

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises,” “comprising,” “includes” and/or “including,” when usedherein, specify the presence of stated features, integers, steps,operations, elements and/or components, but do not preclude the presenceor addition of one or more other features, integers, steps, operations,elements, components and/or groups thereof.

It should also be noted that in some alternative implementations, thefunctions/acts noted may occur out of the order noted in the figures.For example, two figures shown in succession may in fact be executedsubstantially concurrently or may sometimes be executed in the reverseorder, depending upon the functionality/acts involved.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments belong. Itwill be further understood that terms, e.g., those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Portions of example embodiments and corresponding detailed descriptionare presented in terms of program code, software, or algorithms andsymbolic representations of operation on data bits within a computermemory. These descriptions and representations are the ones by whichthose of ordinary skill in the art effectively convey the substance oftheir work to others of ordinary skill in the art. An algorithm, as theterm is used here, and as it is used generally, is conceived to be aself-consistent sequence of steps leading to a desired result. The stepsare those requiring physical manipulations of physical quantities.Usually, though not necessarily, these quantities take the form ofoptical, electrical, or magnetic signals capable of being stored,transferred, combined, compared, and otherwise manipulated. It hasproven convenient at times, principally for reasons of common usage, torefer to these signals as bits, values, elements, symbols, characters,terms, numbers, or the like.

Specific details are provided in the following description to provide athorough understanding of example embodiments. However, it will beunderstood by one of ordinary skill in the art that example embodimentsmay be practiced without these specific details. For example, systemsmay be shown in block diagrams so as not to obscure the exampleembodiments in unnecessary detail. In other instances, well-knownprocesses, structures and techniques may be shown without unnecessarydetail in order to avoid obscuring example embodiments.

Example embodiments are discussed herein as being implemented in asuitable computing environment. Although not required, exampleembodiments will be described in the general context ofcomputer-executable instructions, such as program modules or functionalprocesses, being executed by one or more computer processors or CPUs.Generally, program modules or functional processes include routines,programs, objects, components, data structures, etc. that performsparticular tasks or implement particular abstract data types.

Example embodiments are discussed herein as being implemented in asuitable computing environment. Although not required, exampleembodiments will be described in the general context ofcomputer-executable instructions, such as program modules or functionalprocesses, being executed by one or more computer processors or CPUs.Generally, program modules or functional processes include routines,programs, objects, components, data structures, etc. that performsparticular tasks or implement particular abstract data types.

As disclosed herein, the term “memory,” “storage medium,” “computerreadable storage medium” or “non-transitory computer readable storagemedium” may represent one or more devices for storing data, includingread only memory (ROM), random access memory (RAM), magnetic RAM, corememory, magnetic disk storage mediums, optical storage mediums, flashmemory devices and/or other tangible machine readable mediums forstoring information. The term “computer-readable medium” may include,but is not limited to, portable or fixed storage devices, opticalstorage devices, and various other mediums capable of storing,containing or carrying instruction(s) and/or data.

According to example embodiments, schedulers, hosts, cloud-basedservers, gNB, etc., may be (or include) hardware, firmware, hardwareexecuting software or any combination thereof. In one example, acommunications network may include a plurality of different radiointerfaces, such as 3rd Generation (3G), 4th Generation (4G) and 5thGeneration (5G) interfaces, Wireless Local Area Network (WLAN)standalone hotspots such as WiFi hotspots, and the like, across both thelicensed and unlicensed spectra, as well as across macro cells, metrocells and femto cells.

The schedulers, hosts, servers, gNB, etc., may also include variousinterfaces including one or more transmitters/receivers connected to oneor more antennas, a computer readable medium, and (optionally) a displaydevice. The one or more interfaces may be configured to transmit/receive(wireline and/or wirelessly) data or control signals via respective dataand control planes or interfaces to/from one or more switches, gateways,Mobility Management Entities (MMEs), controllers, gNBs, servers, clientdevices, etc.

While the procedures and embodiments are described primarily in thecontext of a 5G network, it should be noted that they are alsoapplicable to networks following other systems and technologies, such asa fourth-generation or Long-Term (LTE) network.

FIG. 1 illustrates a 3GPP 5G system architecture according to someexample embodiments. FIG. 2 illustrates a Radio Access Network (RAN) ina 5G network according to some example embodiments. FIG. 3 illustrates arelevant portion of the 3GPP 5G system architecture according to someexample embodiments;

Referring to FIGS. 1 to 3, in a fifth generation (5G) communicationssystem 100, functions, reference points, protocols and the like may bedefined by network functions (NFs) rather than by hardware entities. Thesystem 100 may be divided into various planes including a user plane(UP) and a control plane (CP).

The CP functions may include various functions to control a network anduser equipments (UEs). UP functions may include various functions tocontrol processing of data packets sent to or received from the UEs.

The system 100 may include a multitude of network elements in functionsincluding UEs 110, a Radio Access Network (RAN) 120, a User PlaneFunction (UPF) 130, a Access and Mobility Management Function (AMF) 140,a Session Management Function (SMF) 150, and a Network RepositoryFunction (NRF) 160. In addition the system 100 may include otherelements as defined by 3GPP technical specification 23.501, the entirecontents of which is hereby incorporated by reference in its entiretyand illustrated in FIG. 1.

For example, the system 100 may also include a NSSF, NEF, PCF, UDM, AF,AUSF and DN. The NSSF provides a Network Slice Selection Function whichis used for selecting a slice for a given user in a network thatsupports slicing. The NEF is a Network Exposure Function that allowsexternal elements to connect via Application Programming Interfaces(APIs) to various network functions. The PCF is a Policy ControlFunction which enables policy-driven operation for the network. The UDMis a Unified Data Management Function. The AF is an application functionthat provides various services to user equipments. The AUSF is anAuthentication Server Function that handles authentication of userequipments attaching to the network. The DN represents a Data Network,such as the Internet or a private content network. However, while theseother elements are provided for the sake of completeness, these elementsmay not necessarily be relevant to the example embodiments, and thus,will not be discussed in more detail below.

The RAN 120 may have a user plane (UP) and a control plane (CP), and theCore Network may also have a User Plane (UP) and a control plane (CP).

The UPF 130 may be a part of the 5G core network, and may manageprocessing data packets sent to or from the UEs 110. The AMF 140 may bea part of the Control Plane (CP) of the 5G Core Network that performsaccess authentication and authorization when one of the UEs 110 attachesto the network, and may also perform mobility-related operations. TheSMF 150 may be a part of the Control Plane (CP) of the 5G Core networkthat performs session-related functions, such as establishment/releaseof bearers, and also selects the UPF instance that should serve the datapackets of a particular session associated with one of the UEs 110 orflow or bearer. The AMF 140 and the SMF 150 are part of what is referredto as a fifth generation core (5GC) control plane.

The NRF 160 may receive queries from other parts of the 5G system andprovide types of information to the querying entities, for examplerelating to the attributes of a particular network element or networkfunction or a group of UEs 110 or slices.

Referring to FIG. 2, the RAN 120 (also known as a gNB in 5G New Radio(NR) architecture, or as eNB in the LTE network, as described in 3GPPtechnical specification 38.300, the entire contents of which is herebyincorporated by reference in its entirety) may implement a radio accesstechnology. The Radio Access Network may also be based on an airinterface technology other than 5G, NR or LTE.

The RAN 120 may include a Distributed Unit (DU) 122 and a CentralizedUnit (CU) as described in 3GPP specification 38.401, the entire contentsof which is hereby incorporated by reference in its entirety. The CU mayinclude a Centralized Unit-Control Plane (CU-CP) 124 and a CentralizedUnit-User Plane (CU-UP) 126, as described in 3GPP technical report38.806, the entire contents of which is hereby incorporated by referencein its entirety. The CU-UP 126 may perform functions related to theuser-plane data (such as data packets) sent to or from user equipments,including ciphering/encryption, reordering/retransmission,multi-connectivity enabling a user equipment to connect to the networkfrom multiple connection points, and the like. The CU-UP may performcontrol plane functions such as managing the user's radio connection,handovers, signal measurements, and the like.

The DU 122 may perform real-time processing of radio-related/basebandfunctions and the CU may perform non-real-time radio access networkprocedures such as Control Plane (CP) and User Plane (UP).

Collectively, the DU 122, CU-CP 124 and CU-UP 126 may be referred toherein as a New Radio NodeB (NR NodeB), gNodeB, a BS (Base Station), ora next generation node B (gNB) or an eNB (Evolved NodeB). The gNB canprovide access to the 5G Core Network (5GC).

In some example embodiments, the function performed by the CU-UP 126instance may be referred to as a first network function, the functionperformed by the UPF 130 instance may be referred to a second networkfunction, and the function performed by the SMF 150 and/or the NRF 160may be referred to as a third network function. However, the first tothird network functions may not be limited to the CU-UP 126, the UPF 130and the SMF/NRF 150, 160, respectively. For example, the first networkfunction may be performed by any device capable of processing user-planedata for the UE 110 in one portion of the network, the second networkfunction may be performed in various networks by any device capable ofprocessing user-plane data for the UE 110 in another portion of thenetwork, and the third network function may be performed in variousnetworks by and device capable of performing the selection of (or,alternatively, providing information aiding in the selection of) aparticular instance of the first or the second network function forprocessing the user-plane data of the UE 100. More generally, the firstnetwork function may be performed by any device capable of performingany operation in one portion of the network for the UE 110 (such asmobility event processing or security function processing or the like),and the second network function may be performed by any device capableof performing a related operation in another portion of the network forthe UE 110, and the third network function may be performed by anydevice capable of performing a selection of or providing informationaiding in the selection of a particular instance of the first or thesecond network function for performing the relevant operations for theUE 110.

Referring to FIG. 3, the various network functions may be connected viadifferent interfaces. For example, within the RAN 120, an E1 interface(sometimes called an NGx interface) may connect the CU-CP 124 and CU-UP126, an F1 Control plane F1c interface may connect the DU 122 and CU-CP124, and an F1. User plane F1u interface may connect DU 122 and CU-UP126. Further, an N2 interface and N3 interface may connect the RAN 120and the 5G core network, for example, the N2 interface may connect theCU-CP 124 associated with the RAN 120 and the AMF 140 associated withthe 5G core network, and the N3 interface may connect CU-UP 126associated with the RAN 120 and the UPF 130 associated with the 5G corenetwork.

If the Radio Access Network uses radio technologies other than LTE or 5Gor New Radio (NR), typically a network function known as N3IWF mayperform a similar role as the CU-UP 126. The N3IWF may be at leastsomewhat similar to the RAN 120. The N3IWF may interwork so-called‘non-3GPP’ access with the 5GC so that the 5GC treats this ‘non-3GPPaccess’ nearly identically as it does the ‘3GPP-access’. Details of theN3IWF are provided materially in 3GPP technical specification 23.502,the entire contents of which is hereby incorporated by reference in itsentirety.

Further still, a N4 interface may connect the UPF 130 and the SMF 150, aN6 interface may connect the UPF 130 to a data network (e.g., Internetor a private content network), N11 interface may connect the AMF 140 andthe SMF 150, and a Nnrf interface may connect functions within 5GCcontrol plane (e.g., the SMF 150 and NRF 160).

Typically the instances of the UPF 130, AMF 140, SMF 150, and/or NRF 160may be instantiated on one or more processors which may be part of oneor more servers or other suitable network element apparatus. There maybe multiple instances of each of these network functions in the network,and the different instances of the same network function and/ordifferent ones of the network functions may be physically in differentlocations, such as in different racks within a data center, or withingeographically separated data centers.

For example, the instances of CU-CP 124 and/or CU-UP 126 may beinstantiated on a processor which may be part of a server or othersuitable network element apparatus, and the CU-CP 124 and the CU-UP 126instances can communicate with each other by the E1 interface.

Within the RAN 120, there can be multiple CU-UP 126 instances, and theseCU-UP 126 instances may be placed at topologically different locationswithin the network. Having multiple instances of CU-UP 126 allowsefficient load distribution and resiliency to failures. The CU-UP 126instances may also be placed at different locations relative to eachother, at different locations relative to CU-CP 124 instances, and atdifferent locations relative to different DUs 122. This allowsflexibility in selecting one of the CU-UP 126 instances to meet theneeds of a given deployment scenario, given UE 110 and/or flow.

For any given one of the UEs 110, or for a particular bearer or flow ofone of the UEs 110, the network 100 may select a particular UPF 130instance as well as a CU-UP 126 instance to process the packets of thatUE 110 or bearer or flow. The data flow of the packets sent by the UE110 may flow from the UE 110 to the RAN 120 by flowing from the DU 122to the selected CU-UP 126, and then to the selected UPF 130 and out tothe other endpoint of the flow, which may be in the internet forexample.

The selection of the CU-UP 126 instance from among multiple availableCU-UP 126 instances is typically done by the CU-CP 124, and theselection of the UPF 130 instance is typically done by the SMF 150.These respective selection decisions may in general use very differentcriteria and may be based on very different information.

For example, the selection by the CU-CP 124 of a CU-UP 126 may be basedon the information available in the RAN 120 at the CU-CP 124, and may bebased on criteria such as proximity to the DUs 122 to which UEs 110 areconnected, radio conditions, throughput or other load conditions atvarious CU-UP 126 instances, backhaul bandwidth limitations at variousparts of the RAN 120, etc. In contrast, the selection by the SMF 150 ofthe UPF 130 may be based on information available at the SMF 150, whichmay be very different from the information available at the RAN 120 orCU-CP 124 therein. For example, the SMF 150 may be aware of the identityof the UE 110 and additional information related to the user'ssubscription profile and authorization, as well as requested end-to-endbearer attributes, whereas this information is typically not availableat the RAN 120 and/or at the CU-CP 124.

Further, the SMF 150 may use criteria for selection that are verydifferent from the RAN 120. For example, the SMF 150 may be unaware ofthe radio conditions or the throughput or the path constraints such asbackhaul bandwidth limitations in the RAN 120. Thus, conventionally,there may be no coordination between the CU-CP 124 and the SMF 150 whenthe CU-CP 124 selects the CU-UP 126 and the SMF 150 selects the UPF 130.

In some deployments, the UPF 130 instance may be closely associated witha particular CU-UP 126 instance. For example, the UPF 130 instance maybe collocated with or at a low latency from the CU-UP 126 instance. Forexample, both the UPF 130 and the CU-UP 126 may be instantiated on thesame physical processor, or same physical server, or servers within thesame data center, or in the same edge cloud, or on the same networksubnet, etc. There are several advantages to such deployments. Forexample, such a deployment would allow a packet to flow in an optimizedway through the CU-UP processing and the UPF processing with very lowoverhead, providing a highly optimized user plane crossing the RAN 120and the Core network. The N3 interface between the UPF 130 and the CU-UP126 may be implemented in a highly optimized fashion. The UPF 130 andCU-UP 126 may be closely associated to the extent that a single networkelement may be capable of performing the functions of both UPF 130 andCU-UP 126.

In view of the above, the management of the network is significantlysimplified. Further, the latency experienced by a packet when flowingthrough the UPF 130 and the CU-UP 126 can be very low, due to theoptimized processing and/or low latency between the UPF 130 and theCU-UP 126. Further, such example embodiments can have very highcapacity, due to the potential elimination of overheads in processingpackets and passing the processed packets from the UPF 130 to the CU-UP126, as well as lower cost due to the reduced need for intermediateswitches, routers and transport links between the UPF 130 and the CU-UP126.

While as discussed above, the CU-UP and the UPF 130 may be closelyassociated, such optimization may also be performed with the UPF 130 andthe N3IWF for situations where the UEs 110 connect with radio accesstechnologies other than LTE, 5G or NR, and similar advantages can beobtained from that as well.

In the aforementioned example, from the perspective of the UPF 130instance, the closely associated CU-UP 126 instance may likely be apreferred instance, and vice-versa. That is, from the perspective of theUPF 130 instance, if the UPF 130 instance is selected for processing aflow or bearer of the UE 110, then it is preferable or desirable thatthe closely associated CU-UP 126 instance also be selected in acoordinated way for processing the flow or bearer of the UE 110 in theRAN. In some embodiments, a UPF 130 instance may have multiple preferredCU-UP 126 instances, and vice-versa.

However, conventionally, the SMF 150 may select a particular UPF 130that is closely associated with a preferred CU-UP 126 instance but theCU-CP 124 may select a different CU-UP 126 instance other than thepreferred CU-UP 126 instance, because this selection by the CU-CP 124 isnot coordinated with the SMF 150 and preferred instances are notevaluated. Therefore, the UPF 130 instance and a different CU-UP 126instance may be selected leading to a sub-optimal flow of packetstherebetween. For example, as discussed above, each of the UPF 130instance and the selected CU-UP 126 instance (other than the preferredCU-UP 126 instance) may be placed at topologically different locationswithin the network, for example within different racks within a datacenter, or within geographically separated data centers such that theremay be unnecessary latency and overhead in packets transmittedtherebetween.

FIG. 4 is a block diagram illustrating the structure of a serverassociated with a radio access network (RAN) according to some exampleembodiments.

Referring to FIG. 4, a server 400 associated with the RAN 120 mayinclude at least one processor 410 (referred to hereinafter in singularform); a memory 420; and a communications interface 430.

The processor 410 is operatively coupled to the memory 420 and thecommunications interface 430.

The processor 410 may refer to, for example, a hardware-implemented dataprocessing device having circuitry that is physically structured toexecute desired operations including, for example, operationsrepresented as code and/or instructions included in a program. In atleast some example embodiments the above-referenced hardware-implementeddata processing device may include, but is not limited to, amicroprocessor, a central processing unit (CPU), a processor core, amulti-core processor; a multiprocessor, an application-specificintegrated circuit (ASIC), and a field programmable gate array (FPGA).The processor may be configured, through a layout design or execution ofcomputer readable instructions stored in the memory 420, as a specialpurpose computer to perform the functions of the DU 122, CU-CP 124 orthe CU-UP 126. Therefore, a server associated with the radio accessnetwork RAN 120 may be a server configured to host the CU-CP 124, forexample.

While FIG. 4 illustrates a single server 400, one of ordinary skill inthe art will readily appreciate that each of the DU 122 instance, CU-CP124 instance and the CU-UP 126 may be hosted on different servers 400each having the structure illustrated in FIG. 4.

The memory 420 includes at least one of a volatile memory, non-volatilememory, random access memory (RAM), a flash memory, a hard disk drive,and an optical disk drive.

The communications interface 430 may include various interfacesincluding one or more transmitters/receivers connected to one or moreconnections or antennas to respectively transmit/receive (wirelineand/or wirelessly) signals.

FIG. 5 is a block diagram illustrating the structure of a serverassociated with a core network according to some example embodiments.

Referring to FIG. 5, a server 500 associated with the core network mayinclude at least one processor 510 (referred to hereinafter in singularform); a memory 520; and a communications interface 530.

The processor 510 is operatively coupled to the memory 520 and thecommunication interface 530.

The processor 510 may refer to, for example, a hardware-implemented dataprocessing device having circuitry that is physically structured toexecute desired operations including, for example, operationsrepresented as code and/or instructions included in a program. In atleast some example embodiments the above-referenced hardware-implementeddata processing device may include, but is not limited to, amicroprocessor, a central processing unit (CPU), a processor core, amulti-core processor; a multiprocessor, an application-specificintegrated circuit (ASIC), and a field programmable gate array (FPGA).The processor may be configured, through a layout design or execution ofcomputer readable instructions stored in the memory 520, as a specialpurpose computer to perform the functions of the UPF 130, the AMF 140,or the SMF 150. Therefore, a server associated with the core network maybe a server configured to host the UPF 130 or a server configured tohost the SMF 150, for example.

While FIG. 4 illustrates a single server 400, one of ordinary skill inthe art will readily appreciate that each of the UPF 130, the AMF 140,and the SMF 150 may be hosted on different servers 500 each having thestructure illustrated in FIG. 5.

The memory 520 includes at least one of a volatile memory, non-volatilememory, random access memory (RAM), a flash memory, a hard disk drive,and an optical disk drive.

The communications interface 530 may include various interfacesincluding one or more transmitters/receivers connected to one or moreconnections or antennas to respectively transmit/receive (wired and/orwireless) signals.

FIG. 6 is a signal flow diagram illustrating a procedure to enablecoordinated selection of a UPF instance by an SMF and a CU-UP instanceby the RAN, taking into account preferred relationships between certaininstances of UPF and CU-UP, according to some example embodiments.

Referring to FIG. 6, in operation S600, the UPF 130 and the CU-UP 126within the RAN 120 may collect and exchange information at appropriateevents and/or periodically. For example, the UPF 130 and the CU-UP 126may exchange load, latency, and proximity information. In some exampleembodiments, the UPF 130 and the CU-UP 126 may exchange this informationover the N3 interface using additional information elements.

The proximity information may include information related to ageographical or network topology. For example, information indicatingwhether the UPF 130 and the CU-UP 126 are part of the same subnet,physical hardware, edge cloud domain, etc.

In operation S610, the UPF 130 may create (or, alternatively, update) alist of identifiers identifying preferred CU-UP 126 instances, and mayprovide the list of preferred CU-UP identifiers to the SMF 150 via theN4 interface. Along with the list of preferred CU-UP identifiers, theUPF 130 may also provide the SMF 150 with the information related toload, latency and proximity between the UPF 130 and the respective onesof the CU-UPs 126.

In operation S620, the SMF 150 may transmit the list of preferred CU-UPidentifiers and the collected information to the NRF 160 via the Nnrfinterface.

In other example embodiments, operations S610 and S620 may be combinedin a single operation in which the UPF 130 communicates with the NRF 160directly via a new interface (not shown) between the UPF 130 and the NRF160, or via an existing Nnrf interface supported by the NRF 160, totransmit the list of preferred CU-UP instance identifiers and thecollected information, or the CU-UP 126 may communicate directly withthe NRF 160 via a new interface (not shown) between the RAN 120 and theNRF 160, or via an existing Nnrf interface supported by the NRF 160. Inother example embodiments, rather than levering new interfaces, networkfunctions, such as the SMF 150 and/the CU-CUP 126 may be modified tointeract with the NRF 160 using the Nnrf service access point (SAP).

In operation S630, the UE 110 may perform an attach procedure, bysending an Attach request, or may request the creation of a new bearerby sending a bearer setup request to the network 100.

In operation S640, the CU-CP 124 may transmit an Attach or Bearer/Flowsetup Request to the AMF 140, which in turn may notify the SMF 150 ofthe request by one of the UEs 110 to set up a session.

In operation S650, the SMF 150 may select a UPF 130 to process the dataflow of the UE 110. This selection may be based on various attributes orcriteria, which may for example correspond to the user device such aslocation (TAI), desired UE/flow attributes, slice, Quality of Service(QoS), etc., or based on load-balancing criteria amongst multiple UPFinstances.

Pursuant to the selection of the UPF 130, the SMF 150 may query the NRF160 for the list of preferred CU-UP identifiers associated with theselected UPF 130 over the Nnrf interface. In some example embodiments,the SMF 150 instance which queries the NRF 160 may not necessarily bethe same SMF 150 instance that updated the NRF in operation S620.Thereafter, the SMF 150 may transmit a create session request to the UPF130 in order to notify the UPF 130 that it has been selected to processthe flow of data for the UE 110, and receive a create session responsefrom the UPF 130 via the N4 interface. In some example embodiments, thecreate session response from the UPF 130 may include a list of preferredCU-UP instance identifiers.

In operation S660, the SMF 150 may transmit an Initial Context Setup tothe CU-CP 124 to notify the RAN 120 of the completion of the AttachProcedure on the Core network side, and can provide the selected UPFidentifier and provide the RAN 120 with one or more preferred CU-UPidentifiers via the N2 interface.

In operation S670, the CU-CP 124 may select a particular CU-UP 126instance based on the list of preferred CU-UP identifiers. Thisselection of the CU-UP 126 instance by the CU-CP 124 may use the list ofpreferred CU-UP instance identifiers in addition to the criteria theCU-CP 124 would normally use, or in replacement of the criteria theCU-CP 124 would normally use.

In other example embodiments, instead of the SMF 150 querying the NRF160 to obtain a list of preferred CU-UP instance identifiers for theselected UPF 130 instance and providing the list to the CU-CP 124 inoperation S670, the CU-CP 124 may directly query the NRF 160 via a newinterface (not shown) between the RAN 120 and the NRF 160 in order toobtain the list of preferred CU-UP instance identifiers for the selectedUPF 130 whose identifier was provided to the CU-CP in operation S670.

In operation S680, following the decision to select the CU-UP 126instance, the CU-CP 124 may transmit a create session request to theselected CU-UP 126 to notify the CU-UP 126 that it has been selected toprocess the flow of packets for the UE 110, and receive a create sessionresponse from the CU-UP 126 over the E1 interface. The CU-CP 124 mayprovide an identifier or other information regarding the selected UPFinstance 130 in the create session request. The CU-UP 126 may thencreate session context for the flow or bearer of the UE 110, and may usethe knowledge of the identifier of the UPF 130 to invoke specialoptimizations for the user-plane processing that would support theadvantages mentioned earlier, such as lower latency for the packet flow.This enables the UE 110 to attach to the network 100 and be provided anoptimized user-plane processing path for its data flow traversing theUPF 150 and the preferred CU-UP 126 instance.

Therefore, by performing the procedure described with reference to FIG.6, the SMF 150 and the CU-CP 124 may make a coordinated selection of theUPF 130 and the CU-UP 126 respectively, in such a manner that the CU-UP126 instance chosen by the CU-CP 124 is one of the preferred CU-UP 126instances for that UPF 130. This enables the network 100 to obtain allthe benefits of user-plane optimization mentioned earlier, such as lowerlatency, lower processing overhead, and lower cost.

It should be noted that while the above example illustrates thecoordinated selection of UPF 130 and CU-UP 126 instances as occurring atthe time the UE 110 attaches to the network, the coordinated selectionof UPF 130 and CU-UP 126 instances may also be performed at any suitableinstances or events, such as a handover or tracking area update ormobility event of the UE 110, or addition of a new flow or bearer, orcreation of a new slice in the network, or the like.

FIG. 7 is a signal flow diagram illustrating a procedure to enablecoordinated selection of a UPF instance by an SMF and a CU-UP instanceby the RAN, taking into account the preferred relationships betweencertain instances of UPF and CU-UP according to some exampleembodiments.

Referring to FIG. 7, in some example embodiments, the order in which theoperations may be executed differently relative to the exampleembodiment illustrated in FIG. 6. For example, the RAN CU-CP 124 mayselect the CU-UP 126 instance prior to the SMF 150 selecting the UPF 130instance while still enabling coordinated selection of the UPF 130 andthe CU-UP 126 by the SMF 150 and the CU-CP 124 respectively.

Operation S700 to operation S730 may be substantially similar tooperations S600 to S630, discussed supra, and, thus for the sake ofbrevity, repeated descriptions will not be included herein.

In operation S740, the CU-CP 124 may select a CU-UP 126 instance basedon various criteria suitable for the RAN 120, such as radio conditions,bandwidth limitations in the backhaul network, latency or proximitybetween the CU-UP 126 and the DU 122 to which the UE 110 is connected,and the like.

In operation S750, the CU-CP 124 may transmit, via the N2 interface, theattach request from the UE 110 to the Core network (e.g., the AMF 140 orthe SMF 150) such that the attach request further includes an identifierof the selected CU-UP 126 instance.

In operation S760, the SMF 150 may query, via the Nnrf interface, theNRF 160 to obtain a list of UPF 130 instance identifiers for whom theselected CU-UP instance 126 is a preferred CU-UP instance.

In some example embodiments, the SMF 150 instance which queries the NRF160 may not necessarily be the same SMF 150 instance that updated theNRF in operation S720.

Thereafter, at operation S770 the SMF 150 may select a UPF instanceidentifier taking into account the UPF 130 instances for whom theselected CU-UP 126 instance is a preferred identifier, along with othercriteria such as location or tracking area, load-balancing, the needs ofthe bearer or flow for the user equipment 110, and the like. Further,the SMF 150 may transmit, via the N4 interface, a create session requestto the UPF 130 and receive a create session response from the UPF 130.

In operation S780, the SMF 150 or AMF 140 may transmit, via the N4interface, an initial context setup to the CU-CP 124 indicatingattachment is complete, and may additionally include an indication ofwhether the UPF 130 instance selected by the SMF 150 has the originallyselected CU-UP 126 instance as a preferred CU-UP 126 instance or not, oran indication of whether the CU-CP 124 should select a different CU-UP126 instance compared to the originally selected CU-UP 126 instance.

Depending on this additional indication, the CU-CP 124 may select adifferent CU-UP 126 instance, or continue with the originally selectedCU-UP 126 instance. The CU-CP 124 may then transmit, via the E1interface, a create session request to the selected CU-UP 126 instance.The create session request may include information related to the UPF130, such as a tunnel endpoint identifier sometimes known as TNLinformation. The CU-UP 126 may transmit, via the E1 interface, a createsession response to the CU-CP 124. The create session response mayinclude TNL info of the CU-UP 126.

In operation S790, the CU-UP 126 may create a session context for theflow or bearer of the UE 110, and may also invoke special optimizedprocessing of the packet flows towards the indicated UPF 130 asdescribed earlier. This enables the UE 110 to attach to the network andbe provided an optimized user-plane processing path for its data flowtraversing the UPF 150 and the preferred CU-UP 126 instance.

Therefore, by performing the procedure described with reference to FIG.7, the SMF 150 and the CU-CP 124 may coordinate selection of the UPF 130and the CU-UP 126 respectively, in such a manner that the CU-UP 126instance chosen by the CU-CP 124 is one of the preferred CU-UP 126instances for that UPF 130. This enables the network to obtain all thebenefits of user-plane optimization mentioned earlier, such as lowerlatency, lower processing overhead, and lower cost.

As discussed above, in one or more example embodiments, selection of aparticular UPF 130 by the SMF 130, and selection of a particular CU-UP126 instance by the CU-CP 124 may be coordinated such that the selectedUPF 130 instance and CU-UP 126 instance pair may be improved (or,alternatively, optimized).

As discussed above, example embodiments may be implemented over standardinterfaces between various ones of the instances in the 5G network.Alternatively, as discussed above, in one or more other exampleembodiments, a new interface may be established to allow directcommunication between the UPF 130 and the NRF 160 to allow the UPF 130to directly provide the NRF 160 with the list of preferred CU-UPidentifiers. Further still, in one or more other example embodiments, anew interface may be established to allow direct communication betweenthe CU-CP 124 and the NRF 160 to allow the CU-CP 124 to query the NRF160 to obtain preferred CU-UP instance identifiers for a selected UPF130. Yet other embodiments may be implemented in which the SMF 150 mayquery the NRF 160 by providing a selected CU-UP 126 instance identifierand obtain from the NRF a list of UPF instance identifiers for which theselected CU-UP 126 instance identifier is a preferred CU-UP instance.

In some cases, for example where the UE 110 connects to the network by adifferent radio access technology and an N3IWF is used to process theuser-plane packet flow to and from the UE 110, the above methods may beused to effect a coordinated selection of the UPF 130 instanceidentifier by the core network and the selection of the N3IWF instanceby the radio access network. In some example embodiments, the UPF 130instance may be placed in a manner coordinated with the placement of theCU-UP 126 instance, thereby enabling the two to be closely associatedand harness the potential benefits therefrom. This placement istypically performed by an orchestration decision, and this orchestrationmay also be coordinated across the RAN and Core networks. In someexample embodiments, the NRF 160 that is queried variously by the SMF150 or the CU-UP 126 or interfaced to by the UPF 130 or the CU-UP 126may be distributed in various places with data replication or othertechniques, to enable high scalability and fault tolerance.

Benefits, other advantages, and solutions to problems have beendescribed above with regard to specific embodiments of the invention.However, the benefits, advantages, solutions to problems, and anyelement(s) that may cause or result in such benefits, advantages, orsolutions, or cause such benefits, advantages, or solutions to becomemore pronounced are not to be construed as a critical, required, oressential feature or element of any or all the claims.

Reference is made in detail to embodiments, examples of which areillustrated in the accompanying drawings, wherein like referencenumerals refer to the like elements throughout. In this regard, theexample embodiments may have different forms and should not be construedas being limited to the descriptions set forth herein. Accordingly, theexample embodiments are merely described below, by referring to thefigures, to explain example embodiments of the present description.Aspects of various embodiments are specified in the claims.

1. A server associated with a core network, the server comprising: amemory storing computer-readable instructions; and at least oneprocessor coupled to the memory, the at least one processor configuredto execute the computer-readable instructions to, generate a list ofpreferred instances of a first network function, transmit the list ofthe preferred instances to a server associated with a third networkfunction, and receive a request to establish a communication sessionwith a selected instance selected from the list of the preferredinstances, if the server is associated with a selected instance of asecond network function associated with the selected instance of thefirst network function.
 2. The server of claim 1, wherein the firstnetwork function is a Centralized Unit-User Plane (CU-UP) functionhaving a CU-UP instance associated therewith, the list of preferredinstances is a list of preferred CU-UP instances configured to performof the CU-UP function, and the selected instance is a selected CU-UPinstance selected from the list of preferred CU-UP instances, the secondnetwork function is a User Plane Function (UPF) having a UPF instanceassociated therewith and the selected instance of the second networkfunction is a selected UPF instance, and the third network function isat least one of a Session Management Function (SMF) having a SMFinstance associated therewith and a Network Repository Function (NRF)Function having a NRF instance associated therewith.
 3. The server ofclaim 2, wherein the at least one processor is configured to exchangeinformation with a Radio Access Network (RAN) server, the informationincluding one or more of load information of each of the server and theRAN server, latency information of each of the server and the RANserver, and proximity information indicating a distance between theserver and the RAN server.
 4. The server of claim 3, wherein the atleast one processor is configured to generate the list of the preferredCU-UP instances based on the information exchanged with the RAN server.5. The server of claim 3, wherein the at least one processor isconfigured to at least one of: exchange information with the RAN serverover an N3 interface, and transmit the list of the preferred CU-UPinstances to the SMF instance over an N4 interface.
 6. The server ofclaim 2, wherein the at least one processor is configured to generatethe list of the preferred CU-UP instances such that the preferred CU-UPinstances are ones of a plurality of CU-UP instances that are one ormore of (i) relatively closer to the server in regards to geographicalor network topology and (ii) relatively lower in latency to the serveras compared to other ones of the plurality of CU-UP instances.
 7. Theserver of claim 6, wherein the at least one processor is configured torun a UPF instance, the UPF instance being co-located with at least oneof the plurality of CU-UP instances included in the list of thepreferred CU-UP instances.
 8. The server of claim 2, wherein the serveris configured to perform the UPF function for a user equipment (UE), andthe selected CU-UP instance is configured to perform a CU-UP functionfor the UE.
 9. The server of claim 8, wherein the selected CU-UP isselected by the RAN server based on a distance between a CentralizedUnit-Unit Plane (CU-CP) instance associated with the RAN server and theselected CU-UP instance associated and the selected UPF instance. 10.The server of claim 9, wherein the selected CU-UP is co-located with theCU-CP instance associated with the RAN server.
 11. A server associatedwith a Radio Access Network (RAN), the server comprising: a memorystoring computer-readable instructions; and at least one processorcoupled to the memory, the at least one processor configured to executethe computer-readable instructions to, receive a list of preferredCentralized Unit-Unit Plane (CU-UP) instances from a server associatedwith a core network, the list of preferred CU-UP instances containingpreferred CU-UP instances, select a selected CU-UP instance based on thelist of preferred CU-UP instances, and establish a communicationssession with the selected CU-UP instance.
 12. The server of claim 11,wherein the at least one processor is configured to, receive anidentifier of a User Plane Function (UPF) instance from a serverassociated with the core network, and provide the identifier of the UPFinstance to the selected CU-UP instance.
 13. The server of claim 12,wherein the at least one processor is configured to select the selectedCU-UP instance such that the CU-UP instance is co-located with at leastone Centralized Unit-Unit Plane (CU-CP) instance.
 14. The server ofclaim 11, wherein the list of preferred CU-UP instances is generatedbased on information exchanged between the CU-UP instance in the RAN anda User Plane Function (UPF) instance in a Core Network.
 15. The serverof claim 14, wherein the information exchanged between the RAN serverand the Core Network includes one or more of load information of each ofa server in the core network and the RAN server, latency information ofeach of the server in the core network and the RAN server, and proximityinformation indicating a distance between the server in the core networkand the RAN server.
 16. A server associated with a core network,comprising: a memory storing computer-readable instructions; and atleast one processor coupled to the memory, the at least one processorconfigured to execute the computer-readable instructions to, select aUser Plane Function (UPF) instance from among a plurality of UPFinstances, query a Network Repository Function (NRF) instance for a listof preferred Centralized Unit-User Plane (CU-UP) instances, the list ofpreferred CU-UP instances containing preferred CU-UP instances, andtransmit the list of preferred CU-UP instances to a CentralizedUnit-Unit Plane (CU-CP) instance.
 17. The server of claim 16, whereinthe CU-CP instance selects a selected CU-UP instance from among the listof preferred CU-UP instances.
 18. The server of claim 16, wherein the atleast one processor is configured to host a Session Management Function(SMF) instance.
 19. The server of claim 16, wherein the at least oneprocessor is configured to, receive the list of preferred CU-UPinstances from one of the plurality of UPF instances, and transmit thelist of preferred CU-UP instances to the NRF instance prior toperforming an attach procedure with a user equipment (UE).
 20. Theserver of claim 19, wherein the at least one processor is configured to,query the NRF instance for the list of preferred CU-UP instances andtransmit the list of preferred CU-UP instances to the CU-CP instanceafter completing an attachment procedure with the UE.